Abstract: Facultative intracellular Brucella species cause brucellosis in animals and humans and have been classified as NIAID category B priority pathogens. Brucella infects the body via the respiratory tract, the skin, and the digestive tract. There is no Brucella vaccine available for human use. Thus, novel vaccines that are non-infectious to humans but effective in stimulating a broad protective immune response are needed. A nasal vaccine that induces both systemic and mucosal immunities would be ideal. Purified smooth Brucella lipopolysaccharide (LPS) induces protection against virulent Brucella infections in different animal models. Brucella LPS is also much less toxic than that from E. coli and has been used as a vaccine adjuvant to facilitate the induction of HIV antigen specific cell-mediated immune response. Additionally, Brucella Cu/Zn Superoxide Dismutase (SOD) is a protective antigen that induces significant protection against brucellosis when combined with IL-2, overexpressed in a Brucella vaccine, or expressed in DNA or RNA vaccines. We hypothesize that a dual-antigen Brucella vaccine containing both LPS and Cu/Zn SOD, when dosed intranasally with appropriate adjuvant(s), will induce significant levels of LPS- and Cu/Zn SOD-specific Th1 and cell mediated immunity to protect against virulent Brucella infection. The overall goal of this proposal is 1) to develop a dual antigen Brucella vaccine by conjugating B. melitensis LPS and Cu/Zn SOD (LPS-SOD) and 2) to evaluate the immune responses induced when nasally dosed with appropriate adjuvants in a well-established mouse model. This project is expected to generate a novel prototype nasal Brucella vaccine candidate and lay a sound scientific foundation for the development of an efficacious nasal Brucella vaccine for human use. PUBLIC HEALTH RELEVANCE: Brucella species cause debilitating brucellosis in humans and animals and have been listed as pathogens potentially used for bioterrorism. However, there is no Brucella vaccine available for human use. This proposal aims to develop and analyze a novel prototype nasal Brucella vaccine by conjugating two protective Brucella antigens.